Enabling Replicative Immortality
Enabling Replicative Immortality is one of the key Hallmarks of Cancer. Cancer cells have limitless replicative potential. They have therefore breached the in-built replication limit hard-wired into the cell and, disengaged their growth program from the signals in their environment.
Cancer cells have limitless replicative potential. They have therefore breached the in-built replication limit hard-wired into the cell and, disengaged their growth program from the signals in their environment.
All cancer cells are able to achieve this by maintaining their telomeres. 90% of them do so by increasing the production of an enzyme known as telomerase. Telomerase production may be increased by oncoproteins in cancer cells, whilst 10% of cancers rely on activation of the ALT (alternative lengthening of telomeres) pathway that lengthens telomeres. Oxidative stress can also lengthen telomeres.
The characteristic feature of a cancer cell is its ability to divide limitlessly by destroying the telomere or ‘cellular timekeeper’. The association between cancer and aging is through the accumulation of damaging mutations that increases with time. The immortalization of cancer cells by telomere maintenance, therefore, represents an essential step in tumor progression.
The increased risk of breast cancer includes inheritance of mutations in the genes BRCA2 and BRCA1. Individuals with heterozygous mutations in either of these genes are at increased risk of breast, ovarian, and other cancers. The BRCA1 (BReast CAncer gene 1) tumor suppressor protein has many reported functions. In addition to mediating signal transduction in DNA damage and repair responses, BRCA1 regulates transcriptional activity and assists in the preservation of chromosomal stability. The literature reports that BRCA2 mutations increase the risk of breast cancer and has a role in telomere protection and maintenance.
To explore BRCA status in cancer tumors, RNA is an ideal indicator of the dynamic gene expression changes that occur in an organism. A revolutionary assay is available to capture gene expression in situ at a single cell level that can be visualized within intact tissue. This provides molecular detection in a morphological context to better understand cell-to-cell interactions.
The value of RNAScope in assessing gene expression and chromosomal stability is well documented. In a study investigating the therapeutic potential of PARP inhibitors, the functional consequence of BRCA gene mutations was assessed in patient tumor tissue (Naipal et al 2015). The authors performed in situ detection of BRCA1 mRNA was using RNAScope technology. In a more recent study at University of Otago (Lattimore, PhD Thesis 2017), BRCA1 and BRCA2 expression patterns were assessed in lymphoblastoid cell lines using an in situ hybridisation platform, RNAscope to understand the variability of mRNA expression.
RNAscope® is a novel multiplex nucleic acid in situ hybridization technology. ACD's unique patented probe design amplifies target-specific signals but not background noise, delivering clear and actionable results.
A tumor is a complex organ consisting of many cell types. Localization of an alteration in gene expression to specific cell types provides the first link to cellular function. The pursuit of personalized medicine through technologies like microarrays and next-generation sequencing has generated a wealth of novel biomarkers, which promise to improve cancer diagnosis and patient stratification. However, for many of these biomarkers, we do not know which specific cell types in the tumor express them. This limits our ability to fully understand their biological relevance. Furthermore, clinically relevant changes in gene expression in specific cell types may be lost in RNA extraction-based methods such as microarrays and RT-PCR.
Here we summarize the role of novel RNA in situ hybridization technology in expanding the tool-set available to researchers, thereby overcoming the challenges of cancer research in four key areas:
- Analysis of gene expression to understand tumor heterogeneity
- Studying non-coding RNAs
- Developing biomarkers
- Driving and refining the diagnostic strategies of the future
To support cell-based research that explores chromosomal instability in breast cancer, cell lines, and panels that represent oncologically relevant histological and molecular characteristics are powerful tools.
ATCC has developed an extensive collection of breast cancer-related Tumor Cell Panels to complement ATCC’s wide array of individual tumor cell lines. Each ATCC Tumor Cell Panel includes low-passage, authenticated tumor cell lines, which have been annotated with genetic mutation data (from the Catalogue of Somatic Mutations in Cancer database, Wellcome Trust Sanger Institute, UK), and collected together in ways that best represent the specific features of this heterogeneous disease.
We know that in normal cells, each stage of the cell cycle is tightly regulated, however, in cancer cells many genes and proteins that are involved in the regulation of the cell cycle are mutated or over-expressed.
This poster from Tocris Biosciences summarizes the stages of the cell cycle and DNA repair. It also highlights strategies for enhancing replicative stress in cancer cells to force mitotic catastrophe and cell death.
